Background: The role of altered joint mechanics on cartilage degeneration in in vivo models has not been studied successfully due to a lack of pre-injury information. We aimed 1) to develop an accurate in vivo canine model to measure the changes in joint loading and T2 star (T2*) relaxation time before and after unilateral supraspinatus tendon resections, and 2) to find the relationship between regional variations in articular cartilage loading patterns and T2* relaxation time distributions.
Methods: Rigid markers were implanted in the scapula and humerus of tested dogs. The movement of the shoulder bones were measured by a motion tracking system during normal gaits. In vivo cartilage contact strain was measured by aligning 3D shoulder models with the motion tracking data. Articular cartilage T2* relaxation times were measured by quantitative MRI scans. Articular cartilage contact strain and T2* relaxation time were compared in the shoulders before and three months after the supraspinatus tendon resections.
Results: Excellent accuracy and reproducibility were found in our in vivo contact strain measurements with less than 1% errors. Changes in articular cartilage contact strain exhibited similar patterns with the changes in the T2* relaxation time after resection surgeries. Regional changes in the articular cartilage T2* relaxation time exhibited positive correlations with regional contact strain variations three months after the supraspinatus resection surgeries.
Conclusion: This is the first study to measure in vivo articular cartilage contact strains with high accuracy and reproducibility. Positive correlations between contact strain and T2* relaxation time suggest that the articular cartilage extracellular matrix may responds to mechanical changes in local areas.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
This is a list of supplementary files associated with this preprint. Click to download.
Loading...
On 02 Jul, 2020
On 22 Jun, 2020
On 22 Jun, 2020
On 18 Jun, 2020
On 18 Jun, 2020
Posted 16 Jun, 2020
On 15 Jun, 2020
On 15 Jun, 2020
On 14 Jun, 2020
On 14 Jun, 2020
On 08 Jun, 2020
Received 07 Jun, 2020
Received 31 May, 2020
Received 29 May, 2020
On 20 May, 2020
On 18 May, 2020
On 17 May, 2020
Invitations sent on 09 May, 2020
On 29 Apr, 2020
On 24 Apr, 2020
On 23 Apr, 2020
On 02 Jul, 2020
On 22 Jun, 2020
On 22 Jun, 2020
On 18 Jun, 2020
On 18 Jun, 2020
Posted 16 Jun, 2020
On 15 Jun, 2020
On 15 Jun, 2020
On 14 Jun, 2020
On 14 Jun, 2020
On 08 Jun, 2020
Received 07 Jun, 2020
Received 31 May, 2020
Received 29 May, 2020
On 20 May, 2020
On 18 May, 2020
On 17 May, 2020
Invitations sent on 09 May, 2020
On 29 Apr, 2020
On 24 Apr, 2020
On 23 Apr, 2020
Background: The role of altered joint mechanics on cartilage degeneration in in vivo models has not been studied successfully due to a lack of pre-injury information. We aimed 1) to develop an accurate in vivo canine model to measure the changes in joint loading and T2 star (T2*) relaxation time before and after unilateral supraspinatus tendon resections, and 2) to find the relationship between regional variations in articular cartilage loading patterns and T2* relaxation time distributions.
Methods: Rigid markers were implanted in the scapula and humerus of tested dogs. The movement of the shoulder bones were measured by a motion tracking system during normal gaits. In vivo cartilage contact strain was measured by aligning 3D shoulder models with the motion tracking data. Articular cartilage T2* relaxation times were measured by quantitative MRI scans. Articular cartilage contact strain and T2* relaxation time were compared in the shoulders before and three months after the supraspinatus tendon resections.
Results: Excellent accuracy and reproducibility were found in our in vivo contact strain measurements with less than 1% errors. Changes in articular cartilage contact strain exhibited similar patterns with the changes in the T2* relaxation time after resection surgeries. Regional changes in the articular cartilage T2* relaxation time exhibited positive correlations with regional contact strain variations three months after the supraspinatus resection surgeries.
Conclusion: This is the first study to measure in vivo articular cartilage contact strains with high accuracy and reproducibility. Positive correlations between contact strain and T2* relaxation time suggest that the articular cartilage extracellular matrix may responds to mechanical changes in local areas.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Loading...